The presence of a union was also found to push training up the workplace agenda, with more than 230,000 staff having been helped into some form of work-based learning by their union last year.

The report also found unionised workers were less likely to leave their jobs because they were given a voice to solve their problems, and that saved employers up to £143m in recruitment costs.

The TUC report aims to encourage staff who have never thought about joining a union to do so.

TUC general secretary Brendan Barber said: “These are tough times for workers and unions alike, and now more than ever workers need the protection of a union.

“And it’s not just employees who stand to gain from being involved with a union – employers who work closely with union reps know only too well the benefits of having experts in safety, learning and employment law at close call for advice and help should the need arise.”